Kentucky Reports Additional Equine West Nile Cases

WNV is a viral disease transmitted to horses by infected mosquitoes with mortality rates as high as 30-40%.

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The Kentucky State Veterinarian's office announced Oct. 4 that two additional horses have tested positive for West Nile virus (WNV).

"Results of testing reported today (Oct. 4) by Murray State University's Breathitt Veterinary Center and the University of Kentucky's Veterinary Diagnostic Laboratory confirms a diagnosis of West Nile virus affecting two additional equines within Kentucky, bringing to seven the number of cases reported this year," read the statement from Kentucky Equine Programs manager E.S. "Rusty" Ford.

The first, a 16-year-old Paint gelding from Graves County, began showing signs of disease on Sept. 28. He presented with persistent rear-limb ataxia (incoordination) and remained in serious condition as of Oct. 4. The gelding has no WNV vaccination history, Ford's statement said.

The second, a 7-year-old Rocky Mountain Horse mare, developed signs of disease on Sept. 30 and was subsequently euthanized. Her clinical signs included moderate ataxia, lateral recumbency (positioned on her side, unable to rise), and hypersensitivity to touch. The mare also had no WNV vaccination history, Ford said.

With these new cases, Kentucky has now confirmed equine WNV this year in Calloway, Christian, Edmonson, Graves, Hopkins, Lincoln, and Todd counties. All of the affected animals—aside from the euthanized Rocky Mountain Horse mare—are reportedly alive and recovering.

WNV is a viral disease transmitted to horses by infected mosquitoes. Clinical signs for WNV include flulike signs, where the horse seems mildly anorexic and depressed; fine and coarse muscle and skin fasciculations (twitching); hyperesthesia (hypersensitivity to touch and sound); changes in mentation (mentality), when horses look like they are daydreaming or "just not with it"; occasional somnolence (drowsiness); propulsive walking (driving or pushing forward, often without control); and "spinal" signs, including asymmetrical weakness. Some horses show asymmetrical or symmetrical ataxia. Equine mortality rate can be as high as 30-40%.

The United States Department of Agriculture Animal and Plant Health Inspection Service reported 627 cases of WNV in U.S. horses in 2012; 13 cases were reported last year in Kentucky.

About the Author

Erica Larson, news editor, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in eventing with her OTTB, Dorado.

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